1. Field of the Invention
The present invention relates to a lubrication structure for an engine, and particularly to a lubrication structure for an engine which includes a cartridge type mission gear mechanism.
2. Description of Background Art
In a lubricating system in a conventional mission gear mechanism, a path for lubricating oil supply to a main shaft (countershaft) and a countershaft (driving shaft) of the lubricating system in the mission gear mechanism is configured normally from a path or a groove formed in a wall portion of a mission case or in a wall thickness portion of a mission holder (mission case cover), and supply of lubricating oil to the main shaft or the countershaft is carried out through a predetermined branching path portion or the like from an engine main gallery.
Further, since the route of the lubricating oil path formed so as to extend through the inside of the wall of the mission case or in the wall thickness portion or the mission holder is complicated, it is frequently formed as an opening of the path which is open in an end wall portion of the mission case or the mission holder. The path opening which is in the open state is closed by suitable means to form a path for lubricating oil supply, and supply of lubricating oil to the main shaft or the countershaft is carried out frequently through such a branching path portion as described above.
Further, a structure is disclosed wherein, in the formation of the oil supplying path described above, the path opening is closed by attachment of the mission holder to form an oil supplying path (see, for example, Japanese Patent Laid-Open No. 2004-308775).
In this manner, in the conventional lubricating oil supplying path to a mission gear mechanism, not only a structure of forming a complicated oil supplying path in a mission case or a mission holder is adopted but also a forced lubricating system such as an oil jet is required. As a result, there is a subject of complication of a crankcase and increase of the number of parts.